The present invention relates to an antenna structure comprising an antenna element formed of a conductive foil.
A first example of a related-art antenna structure will be described with reference to FIGS. 14A to 14D.
In this example, an antenna element 10 is formed of sheet material having elasticity such as brass and phosphor bronze, having a thickness of 0.1 to 0.2 mm, and arranged on an outer peripheral face of a core member 12 to be appropriately fixed by adhesion or the like. In an electrical contact part 10a of the antenna element 10, a slit 10b is formed by cutting, as shown in FIG. 14B. The core member 12 is provided with a conductive pin 12a projecting so as to be opposed to the slit 10b to be press-fitted thereinto as shown in FIG. 14C. Since the antenna element 10 is formed of the sheet material having elasticity, the conductive pin 12a is elastically clamped by the slit 10b, so that the antenna element 10 is electrically connected to the conductive pin 12a. The antenna element 10 is appropriately supplied with power by way of this conductive pin 12a. 
In this example, in a case where the outer peripheral face of the core member 12 has a truncated conical shape or a cylindrical shape, edges of the antenna element 10 are liable to peel off from the outer peripheral face because of elasticity of the antenna element itself, as shown in FIG. 14D, even though the antenna element 10 has been adhered along the outer peripheral face. In such a case, the property of the antenna may change.
A second example of the related-art antenna structure will be described with reference to FIGS. 15A and 15B. This example is proposed to overcome the above inconvenience.
As shown in FIG. 15A, an antenna element 14 formed of a conductive foil made of a copper foil having a thickness of 0.04 mm is provided with an aperture 14b in a section to be an electrical contact part 14a. As shown in FIG. 15B, the conductive pin 12a projected from the core member 12 is inserted into the aperture 14b, so that electrical connection is established between this conductive pin 12a and the electrical contact part 14a by soldering 16.
However, not only the annoying soldering work is required, but also there is a probability that electrical connection of the antenna element 14 may become unstable if there is a defect in the soldering part 16.